Process of preparing tetraaryl tin



United States Patent 3,067,225 PROCESS OF PREPARING TETRAARYL TIN Eugen Reindl and Klaus Boidol, Burgkirchen an der All,

Germany, assignors to Farbwerke Hoechst Aktiengeselischaft vormals Meister Lucius & Briining, Frankfurt am Main, Germany, a company of Germany No Drawing. Filed Jan. 14, 1958, Ser. No. 708,748

Claims priority, application Germany Jan. 18, 1957 3 Claims. (Cl. 260-4293) it is known to prepare tin tetraaryl compounds by reaction of tin tetrahalide with sodiumaryl or with chlorobenzene and metallic sodium. A part of the tin tetrahalide is reduced to the stanno stage or to metallic tin. For this reason, the yields mentioned in the literature scarcely exceed 65% of the theoretical yield calculated upon the tin tetrachloride used.

The present invention relates to a process leading to much more favorable yields of 85-90% of the theoretical yield calculated upon the tin tetrahalide used. The process is based on the surprising observation that an aryl-tin halide, particularly diaryl-tin halide, but also triaryl-tin monohalide or monoaryl-tin trihalide, reacts in a more favorable manner with aryl alkali metal than tin tetrahalide. According to the invention, a part of the tin tetraaryl compound, the desired end product, disproportionates with tin tetrahalide to give an aryl-tin halide (cf. Kocheshkov, Ber. 62, 996 and 67, 1348) and this disproportionation product is then reacted with aryl alkali metal to form the tin tetraaryl compound. In the case of the diaryl-tin dihalide the process operates according to the following reaction scheme R Sn+SnX4+2R SnX ZRQSII (R=aryl, X=halogen, Y: alkali metal) As regards the stoichiometry, this process corresponds completely to the hitherto known and used reaction but with the decisive difference that the new two-phase reaction avoids the disturbing reductions and, therefore, gives much higher yields. A certain portion of tetraaryl tin that depends on the amount of the starting material continuously circulates in the process, unchanged in its quantity.

The first reaction phase, viz. the disproportionation of the tetraaryl tin, is carried out at temperatures above 200 C., advantageously between 220 and 230 C. The second phase, viz. the reaction of the aryl-tin halide with aryl alkali metal to yield the tin tetraaryl compound, takes place at temperatures between 20 C. and +80 C., preferably between +4 C. and +5 C. In this case it is advisable to apply the aryl alkali metal in an excess of -25%.

As alkali metal aryl compounds may be used aryllithium and aryl-potassium.

The following examples serve to illustrate the invention but they are not intended to limit it thereto:

Example 1 1st phase: 1280 grams of tetraphenyl tin are slowly heated with 782 grams of tin tetrachloride to 220-230 C. and maintained for 2 hours at this temperature. After cooling, the reaction product is dissolved in 1200 cc. of benzene;

2nd phase: Phenyl sodium obtained from 690 grams of metallic sodium and 1820 grams of chlorobenzene is suspended in 2500 cc. of benzene and the solution obtained under (1) is added dropwise while stirring at 5-6 C. within about 2 hours. After the exothermic reaction has subsided, the reaction mixture is heated to 3,067,225 Patented Dec. 4, 1962 'ice about C., refluxed for 30 minutes and, after cooling, freed from sodium chloride by washing with water and then extracted by means of toluene. Tetraphenyl tin crystallizes from the toluene upon concentration. It is obtained in the form of white to weakly yellow needles melting from 223-224" C. The yield amounts to 2413 grams of pure tetraphenyl tin corresponding to 88.4% of the theoretical yield and calculated upon the tin tetrachloride used.

Example 2 Instead of the phenyl sodium used in Example 1, there may also be used phenyl potassium that is obtained by reaction of 1820 grams of chlorobenzene with potassium.

The method of working and the starting materials used a are the same as indicated in Example 1.

The yield amounts to 89.5% calculated upon tin tetrachloride.

Example 3 967 grams of tetra-para-tolyl-tin are reacted within 3 hours at 240 C. with 532 grams of tin tetrachloride to mainly di-para-tolyl-tin-dichloride and the reaction product is dissolved in 800 cc. of benzene. To this solution is slowly added, while stirring and permanently cooling to +5 C., a suspension of para-tolyl-sodium obtained from 460 grams of sodium, 1365 grams of para-chlorotoluene or 1845 grams of para-bromotoluene and 1800 cc. of benzene. After a reaction period of about 3 hours the reaction mixture is refluxed for about 30 minutes. The tetra-para-tolyl-tin thus obtained is worked up as described in Example 1. There are obtained 1750 grams of tetra-para-tolyl-tin melting at 235-236 C.

The yield amounts to calculated upon tin tetrachloride. Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

We claim:

1. In the process of manufacturing tetraaryl tin from tin tetrachloride and aryl alkali metal, a method of raising the yield of tetraaryl tin to at least 80%, calculated upon the tin tetrachloride used, which comprises combining in a first step at a temperature between 200 and 230 C. tin tetrachloride and tetraaryl tin to form an aryl-tin chloride, and reacting in a second step the aryltin chloride so obtained with aryl alkali metal at a temperature between +4 and +5 C. to form tetraaryl tin, said aryl being a member selected from the group consisting of phenyl and tolyl, and said alkali metal being a member selected from the group consisting of sodium, potassium and lithium.

2. A process according to claim 1 wherein the steps are carried out in a medium of inert solvent.

3. A process as claimed in claim 1 wherein the aryl alkali metal is applied in an excess of 20 to 25% calculated' on the stoichiometric amount required for the reaction with aryl-tin chloride formed in the first step.

References Cited in the file of this patent UNITED STATES PATENTS 2,431,038 Harris Nov. 18, 1947 2,570,686 Johnson et a1 Oct. 9, 1951 2,599,557 Johnson et al June 10, 1952 OTHER REFERENCES Austin: J.A.C.S. 54, 3726-3729 (1932).

Kozeschkow: Chem. Berichte, 66, pages 1661-4665 (1933).

Coates: Organo-Metallic Compounds, New York, John Wiley & Sons, Inc., 1956, page relied on. 

1. IN THE PROCESS OF MANUFACTURING TETRAARYL TIN FROM TIN TETRACHLORIDE AND ARYL ALKALI METAL, A METHOD OF RAISING THE YEILD OF TETRAARYL TIN TO AT LEAST 80%, CALCULATED UPON THE TIN TETRACHLORIDE USED, WHICH COMPRISES COMBINING IN A FIRST STEP AT A TEMPERATURE BETWEEN 200 AND 230*C. TIN TETRACHLORIDE AND TETRAARYL TIN TO FORM AN ARYL-TIN CHLORIDE, AND REACTING IN A SECOND STEP THE ARYLTIN CHLORIDE SO OBTAINED WITH ARYL ALKALI METAL AT A TEMPERATURE BETWEEN +4 AND +5*C. TO FORM TETRAAYL TIN, SAID ARYL BEING A MEMBER SELECTED FROM THE GROUP CONSISTING OF PHENYL AND TOLYL, AND SAID ALKALI METAL BEING A MEMBER SELECTED FROM THE GROUP CONSISTING OF SODIUM, POTASSIUM AND LITHIUM. 